Cable control system having tension controlling means including means to automatically clutch and declutch cable winch



Aug- 31, 1965 F. H. NoRRls ETAL 3,203,673

CABLE CONTROL SYSTEM HAVING TENSION CONTROLLING MEANS INCLUDING MEANS TO AUTOMATICALLY CLUTCH AND DECLUTCH CABLE WINCH Filed Sept. 28, 1962 2 Sheets-Sheet 2 ELE E zNvENToRs. FRED H. NoRR\s BY NORMAN C. ZETER TTORNEYS United States Patent Office Patented Aug. s1, 1965 CABLE CNTROL 'SYSTEM HAVING TENSION CONTRGLLING MEAN'S INCLUDING MEANS TO AUTOMATICALLY CLUTCH AND DECLUTCH CABLE WINCH Fred H. Norris, Elmwood, and Norman C. Zeter, Peoria, Ill., assignors to Caterpillar Tractor Co., Peoria, Ill., a corporation of California Filed Sept. 28, 1962, Ser. No. 226,818 6 Claims. (Cl. 254--173) This invention relates to a cable control system and more particularly relates to a control means for preventing cable breakage when the tension therein exceeds a predetermined amount.

The problem of preventing breakage of the bowl cable of an earth moving apparatus of the type shown in Patent No. 2,722,760, for example, is particularly prevalent where the scraper of such a bowl engages a relatively immovable object such as a tree stump or the like. Such a bowl is adapted to be lowered into scraping contact with the earth to effect a loading of material therein. Once such material is loaded, the cable functions to lift the bowl to its carrying position whereafter the material is transported to a suitable place of disposal. During the bowl raising phase of this operation, the scraper or other part of the bowl may become engaged with an immovable type object to thus place the cable under extreme tension. Such a disadvantageous condition ofttimes causes the cable to break or causes damage to interrelated elements of the vehicle. Many attempts have been made to compensate for such possible damage by employing suitable de-clutching mechanisms which are responsive to relieve a detrimental amount of cable tension.

This invention has overcome many of the above-mentioned diiculties by providing a cable control system which employs a control means comprising first and second pivotally connected members, a cable carrying sheave mounted on the rst member and means operatively associated with the members and responsive to a predetermined maximum cable tension for relieving such tension to prevent cable breakage.

An object of this invention is to provide a cable control system for preventing Cable breakage.

Another object of this invention is to provide a cable control system for the bowl of an earth moving apparatus for preventing an overloading of the cable thereof.

A further object of this invention is to provide a cable control system which will expeditiously disengage or engage a bowl clutch of an earth moving apparatus in response to the bowl cable tension.

A still further object of this invention is to provide a cable control system which is durable and relatively simple in construction, but yet very eicient in operation.

Other and more specific objects of this invention will become apparent from the following description taken in connection with the drawings wherein:

FIG. 1 is a side elevational view partially broken away of an earth moving apparatus employing the cable control system of this invention;

FIG. 2 discloses a control device used in the cable control system of FIG. 1, with parts broken away for clariication;

FIG. 3 is a cross-sectional view taken on line III-Ill in FIG. 2; and

FIG. 4 is a schematic view illustrating the cable control system concepts of this invention as they would appear in their operative arrangement with a clutch control lever.

FIG. l is an elevational view of a conventional earth moving apparatus, similar to the one disclosed in the above mentioned Patent No. 2,722,760. The apparatus comprises a bowl 10 having side walls 11 and a bottom wall 12 providing a forwardly extending cutting edge 13. An axle 14 pivotally mounts the bowl and also journals a ground engaging wheel 15. An ejector 16 is arranged in the bowl for the purpose of ejecting material therefrom when an apron 17 is raised by means of laterally spaced side arms 18 which are pivotally mounted on stub shafts 19.

The bowl assembly is connected to a draft arm 20 of the scraper by means of side arms 21 of a draft frame and a tubular cross brace 23. A first cable 24 is carried by a suitable actuating drum (not shown), mounted on the vehicle. This cable is trained over a rotatable sheave 25 and then suitably secured to the ejector 16 and apron 17 (not shown) to actuate them in a well known manner.

A second cable 26 is wound upon a rotary drum 27 which may be suitably connected to a power take-olf of the vehicle (not shown) to be payed out and taken in thereby in a well known manner. A conventional clutch 27a and brake mechanism (not shown) may be operatively connected to the drum 27 to control its movements, also in a well-known manner. The cable 26 is trained over sheaves 23, 29, 30, 31, and 32 and is secured by an anchor 33 to a sheave block 34 carried by the draft arm. The sheave 32 is rotatably mounted in a sheave block 35 which is pivotally connected to a spreader beam 36 secured between the forward ends of the bowl side walls 11. It can be seen that a clockwise rotation of drum 27 will eifect a raising of the bowl about the center of axle 14.

Novel concepts of this invention comprise a control means 40 (FIG. 1) which is operatively associated with sheave 28 and cable 26 for selectively actuating or deactuating a lever 41 (FIG. 4) of clutch 27a of drum 27 when the cable tension becomes excessive. The control means, as shown in FIG. 4, comprises a first member 42 adapted to move relative to a second member 43 under a predetermined amount of cable tension to engage a spool member 44 which is slidably mounted in a bore formed in the first member with an adjustable stop member 45. When the spool engages the stop member, passage means comprising uid passages 46 and 47 which communicate through said bore, relieve the uid pressure in a clutch booster 48 to permit clutch lever 41 to disengage the clutch. As will be hereinafter more fully understood, the clutch will remain deactuated so long as the cable tension remains above a predetermined value.

As shown in FIG. 2, the control means more specifically comprises a journal shaft 49 which is ixed to member 42, shown in the form of a bifurcated lever. The sheave 28 is rotatably mounted on shaft 49 by roller bearings 50. A sheave guard 51 comprises a hollow shaft 52 journalled for limited swinging movements onto an arm-like extension or sheave tower 53 of the vehicle. As more clearly shown in FIG. 3, the sheave guard substantially encloses the sheave 28 in order to prevent the cable 26 from slipping oil the sheave.

The laterally spaced arms of second member 43 are welded or otherwise secured at 54 to the sheaved guard, as shown in FIG. 2. A pivot means 55 comprising lobe portions formed on the arms of member 42 and cooperating arcuate recesses formed in the arms of member 43 afford limited pivotal movement between these members. The lower extremity of the members carry cup shaped spring retainers, which are adapted to retain compression springs 56 and 57 and a limit bolt 58. With such an arrangement, the springs function to urge and pivot member 42 away from member 43 about pivot means 55, against the tension created in cable 26. It should be understood that suitable tolerances may be provided in a the system to assume such desiderata. For example, a suitable tolerance is provided between limit bolt 58 and member 42 (FIG. 2) to permit limited relative movements therebetween. Also, a suitable tolerance is provided between the sheave guard 51 and shaft 49, as more clearly illustrated in FIG. 3.

As shown in FIG. 2 should the cable 26 exert sufficient force on the system to pivot member 42 towards member 43, against the biasing effects of springs 56 and 57, the spool 44 will engage stop 45 and be moved in a leftward direction. Suicient movement of the spool will permit passages 46 and 47 to communicate with each other to deactuate the clutch controlling drum 27 to thus relieve the tension on cable 26.

Referring more specifically to FIG. 4, an apertured guide and stop 59 is secured to member 43 and limits the leftward movement of spool 44. Also, when the member 42 is subsequently moved away from member 43, the guide 59 functions to return the spool to the normal position shown in this figure. As will be hereinafter more fully understood, such an arrangement prevents disadvantageous hunting effects which are prevalent in conventional systems. Also, suitable spring arrangements (not shown) may be employed to aid in this function.

Referring once again to FTG. 4, a tension spring 64 is arranged to urge the clutch lever 41 into disengaged position. Such a condition of clutch disengagement may be achieved by maintaining a plunger 65 in the position shown. The plunger is secured to a lever 66 which is in turn connected to a reciprocating rod 67. The rod may be connected through suitable linkages to an operators hand controlled lever or the like. The plunger is thus adapted to be moved to close a bypass passage 68 formed in a piston 69 of the clutch booster 48. As will be hercinafter more fully understood, when the plunger is in the position shown in FG. 4, the pressure in the actuating chamber of the clutch booster is relieved through a return passage 70, arranged to communicate with a fluid supply tank 71 to thus permit the clutch lever 41 to rotate in a counter-clockwise direction under the biasing force of spring 64.

When the lever 66 is rotated in a clockwise direction to close passage 68 with plunger 65, pressure is permitted to build up in the actuating chamber of the clutch booster due to the flow of pressurized uid received therein from supply tank 71, through positive displacement pump 72, conduit 73, flow divider 74 and inlet conduit 7S. A conduit 76 is arranged to communicate with ow divider 74 and may be arranged in operative association with another clutch booster of the overall system.

Simultaneously with the ow of pressurized fluid to the cluutch booster, fluid is also discharged to a combination relief and by-pass valve assembly 77 by means of conduits 78 and 79. A spool S0 is slidably mounted in the assembly and urged in a leftward direction as viewed in FIG. 4 by means of a compression spring 81. So long as the pressure directed through conduits 78 and 79 and acting on opposite ends of spool 80 is equal, fluid is not permitted to be by-passed through the valve assembly from inlet conduit 78 to a discharge conduit 82. A plunger 83 is conventionally arranged to close a central passage 84 of the spool, under the biasing force of a spring 85. When pressure in the circuit reaches a predetermined value sufcient to overcome the force of spring 85, plung` er 83 will be moved leftward to vent the pressure in the chamber of spring 81 through passage 84, radial ports 86 and the return conduit 82 to create a pressure differential in opposite ends of the bore of valve 77. Thus the spool 80 is shifted rightward against the force of spring 81 to establish communication between the conduits 78 and 82 and by-pass the pump discharge to tank 71.

In operation, should the tension in cable 26 exceed a predetermined value spool 44 of FIG. 4 is moved in a leftward direction pursuant to the conditions above described. Passages 46 and 47 thus communicate to relieve the fluid CTI pressure received in the valve assembly 77 through conduit 79. This permits spool 30 to be shifted in a rightward direction to by-pass the discharge of pump 72 and relieves the pressure in clutch booster 48 to disengage the clutch of drum 27 and relieve the tension in cable 26. A ow control orifice 87 is formed in conduit 73 to regulate the amount of fluid directed to clutch booster 48. Should the output of pump 72 exceed the capacity of orice 87, the resultant pressure differential moves spool to the right an amount sufficient to by-pass the excess volume of uid as previously described.

The cable drum 27 is generally also provided with a conventional slip type control brake (not shown). Upon disengagement of the drum clutch, such a brake may be arranged to permit a limited slippage of the drum to thus relieve the tension on cable 26. Once the cable tension is reduced below a predetermined amount, springs 56 and 57 will function to pivot member 42 relative to member 43 and return the spool 44 to its original position 'of FIG. 4. The distance provided between the stop 45 and guide 59 permits a time lag which prevents hunting or sudden jerking to occur in the system before the enlarged portion 60 of the spool engages with guide 59 to return the spool back to its original position. It should be noted that spool 44 may be fitted within member 42 with sufficient friction to cause them to move together unless movement of the spool is interrupted.

We claim:

1. A cable control system comprising a rst member arranged for movement towards or away from a second member, a tensioned cable operatively engaging said first member for urging said first member towards said second member, biasing means arranged for urging said iirst member away from said second member and means for constantly sensing and regulating the amount of cable tension to automatically pay out said cable when cable tension exceeds a predetermined amount and for automatically stopping the paying out of said cable when the tension thereof is relieved below said predetermined amount, said means including a valve means mounted on one of said members in operative engagement with dual stop means mounted on the other of said members, said stop means being so mounted that when said members are moved a predetermined distance away in one direction one of said stops operates to open said valve and when said members are moved away a predetermined distance in the opposite direction the other of said stops operates to close said valve.

2. A cable control system according to claim 1 wherein the valve means includes a spool member slidably mounted in a :duid flow bore said spool member acting in response to said stop means to open and close said bore.

3. A cable control system according to claim 1 wherein said rst and second members are connected by pivot means.

4. A cable control system according to claim 2 wherein iirst and second passages are arranged in communicating relationship with said bore whereby a uid is adapted to flow between said passages through said bore when said spool member acts to open said bore.

5. A cable control system according to claim 1 wherein the valve means are mounted on said rst member and said stop means are mounted on said second member.

6. A cable control system according to claim 5 wherein said cable is trained over a sheave mounted on said first member.

References Cited by the Examiner UNTTED STATES PATENTS 2,683,020 7/54 Nickle 254-173 2,846,788 8/58 Vance 37-126 3,043,566 7/62 Grise 37-126 BENJAMIN HERSH, Primary Examiner. 

1. A CABLE CONTROL SYSTEM COMPRISING A FIRST MEMBER ARRNAGE FOR MOVEMENT TOWARDS OR AWAY FROM A SECOND MEMBER, A TENSIONED CABLE OPERATIVELY ENGAGING SAID FIRST MEMBER FOR URGING SAID FIRST MEMBER TOWARDS SAID SECOND MEMBER, BIASING MEANS ARRANGED FOR URGING SAID FIRST MEMBER AWAY FROM SAID SECOND MEMBER AND MEANS FOR CONSTANTLY SENSING ANS REGULATING THE AMOUNT OF CABLE TENSION TO AUTOMATICALLY PAY OUT SAID CABLE WHEN CABLE TENSION EXCEEDS A PREDETERMINED AMOUNT AND FOR AUTOMATICALLY STOPPING THE PAYING OUT OF SAID CABLE WHEN THE TENSION THEREOF IS RELIEVED BELOW SAID PREDETERMINED AMOUNT, SAID MEANS INCLUDING A VALVE MEANS MOUNTED ON ONE OF SAID MEMBERS IN OPEARATIVE ENGAGE MENT WITH DUAL STOP MEANS MOUNTED ON THE OTHER OF SAID MEMBERS, SAID STOP MEANS BEING SO MOUNTED THAT WHEN SAID MEMBERS ARE MOVED A PREDETERMINED DISTANCE AWAY IN ONE DIRECTION ONE OF SAID STOPS OPERATES TO OPEN SAID VALVE AND WHEN SAID MEMBERS ARE MOVED AWAY A PREDETERMINED DISTANCE IN THE OPPOSITE DIRECTION THE OTHER OF SAID STOPS OPERATES TO CLOSE SAID VALVE. 